Expert Estimation of Web-Development Projects: Are Software Professionals in Technical Roles More Optimistic Than Those in Non-Technical Roles?

Abstract

Estimating the effort required to complete web-development projects involves input from people in both technical (e.g., programming), and non-technical (e.g., user interaction design) roles. This paper examines how the employees' role and type of competence may affect their estimation strategy and performance. An analysis of actual web-development project data and results from an experiment suggest that people with technical competence provided less realistic project effort estimates than those with less technical competence. This means that more knowledge about how to implement a requirement specification does not always lead to better estimation performance. We discuss, amongst others, two possible reasons for this observation: (1) Technical competence induces a bottom-up, construction-based estimation strategy, while lack of this competence induces a more “outside” view of the project, using a top-down estimation strategy. An “outside” view may encourage greater use of the history of previous projects and reduce the bias towards over-optimism. (2) Software professionals in technical roles perceive that they are evaluated as more skilled when providing low effort estimates. A consequence of our findings is that the choice of estimation strategy, estimation evaluation criteria and feedback are important aspects to consider when seeking to improve estimation accuracy.